Hypothetical assessment of efficiency, willingness-to-accept and willingness-to-pay for dengue vaccine and treatment: a contingent valuation survey in Bangladesh

Unveiling the complexity of vaccine hesitancy: A narrative review focusing on dengue vaccination

Dengue vaccines face significant challenges, including safety concerns, which contribute to vaccine hesitancy. Addressing this complex issue requires targeted strategies to overcome existing barriers. Through an extensive review of current evidence, we identified key factors contributing to vaccine hesitancy and explored strategies to enhance global vaccine uptake. Four conceptual models and five assessment tools were identified to understand and measure vaccine hesitancy. Among the factors, "confidence" emerged as the most influential, followed by "complacency." Vaccine acceptance rates varied widely, ranging from 53% to 95%, depending on the region and population. Key determinants included population characteristics, concerns about efficacy and safety, among others. A comprehensive understanding of these factors is essential to improve vaccine acceptance, support dengue prevention efforts, and ensure public health success.

Bamboo stumps that are artificially in use put pressure on dengue and chikungunya vector control in Dhaka city, Bangladesh

BACKGROUND OBJECTIVES

Aedes aegypti and Ae. albopictus mosquitoes breed in natural and artificial containers, and they transmit dengue and chikungunya. A study was conducted to identify the contribution of bamboo stumps to these disease vectors that were used in the flower garden as pillars to hold the bamboo flex fence.

METHODS

Two sizes of whole bamboo were used to hold fences around gardens at Dhaka University, Bangladesh, and were painted red and green. Mosquito larvae and pupae were collected from bamboo stumps between July and August, and vectors were identified up to the species level. The data were analyzed using the STATA/MP 14.2 version.

RESULTS

83.5% and 0.2% were Ae. albopictus and Ae. aegypti, respectively, and the remaining were Culex and Ar-migeres species. Ae. albopictus, Ae. aegypti, and both species-positive bamboo stumps were 46.9, 0.7, and 47.1%, respectively. 54.5% of the bamboo stumps had at least one mosquito species. The average stump depth for Aedes positive stumps (mean=11.7 cm, SE = 0.5) was significantly (p <0.001) higher than the Aedes negative stumps (mean = 9.5 cm, SE = 0.4). 53.8% and 38.0% stumps were found Aedes positive on the ground and upper sides of fences, respectively, and found significant (p<0.01) differences between both sides. A zero-inflated negative binomial count model is significant at a 5% level of significance, χ2(4) = 11.8, p = 0.019 (<0.05) for Ae. albopictus. Stump depth is found to have a significant positive effect on the number of Aedes-positive stumps.

INTERPRETATION CONCLUSION

Artificially used natural containers are adding pressure to current mosquito control activities as mosquitoes are breeding on them, which needs additional attention.

Modelling the impact of human behavior using a two-layer Watts-Strogatz network for transmission and control of Mpox

PURPOSE

This study aims to evaluate the effectiveness of mitigation strategies and analyze the impact of human behavior on the transmission of Mpox. The results can provide guidance to public health authorities on comprehensive prevention and control for the new Mpox virus strain in the Democratic Republic of Congo as of December 2023.

METHODS

We develop a two-layer Watts-Strogatz network model. The basic reproduction number is calculated using the next-generation matrix approach. Markov chain Monte Carlo (MCMC) optimization algorithm is used to fit Mpox cases in Canada into the network model. Numerical simulations are used to assess the impact of mitigation strategies and human behavior on the final epidemic size.

RESULTS

Our results show that the contact transmission rate of low-risk groups and susceptible humans increases when the contact transmission rate of high-risk groups and susceptible humans is controlled as the Mpox epidemic spreads. The contact transmission rate of high-risk groups after May 18, 2022, is approximately 20% lower than that before May 18, 2022. Our findings indicate a positive correlation between the basic reproduction number and the level of heterogeneity in human contacts, with the basic reproduction number estimated at 2.3475 (95% CI: 0.0749-6.9084). Reducing the average number of sexual contacts to two per week effectively reduces the reproduction number to below one.

CONCLUSION

We need to pay attention to the re-emergence of the epidemics caused by low-risk groups when an outbreak dominated by high-risk groups is under control. Numerical simulations show that reducing the average number of sexual contacts to two per week is effective in slowing down the rapid spread of the epidemic. Our findings offer guidance for the public health authorities of the Democratic Republic of Congo in developing effective mitigation strategies.

Dengue vaccine acceptance and willingness to pay: a systematic review and meta-analysis

OBJECTIVE

Dengue is the most important human vector-borne disease in terms of disease burden. A first dengue vaccine has recently been licenced, and others are in advanced stages of development. However, to date, none of these vaccines has achieved balanced efficacy and safety for all dengue serotypes. The aim of this systematic review and meta-analysis was to assess the global acceptance and willingness to pay for unspecified dengue vaccines.

METHODS

This systematic review and meta-analysis included cross-sectional and cohort studies that reported values for vaccine acceptance (percentage) and willingness to pay for currently available or hypothetical vaccines. These values were pooled using random-effects models for the acceptance, while weighted linear regression was chosen for willingness to pay. Heterogeneity between studies was assessed using prediction intervals (PIs), and a domain-based tool was used to assess the risk of bias. Subgroup and sensitivity analyses were performed where appropriate. This study was registered with PROSPERO (CRD42021255784).

RESULTS

We included 19 studies from the Americas and Asia in the quantitative meta-analysis. The risk of bias was mainly related to the selection of participants and to the assumptions about the safety and efficacy of the vaccines. The percentage of vaccine acceptance was 88.3% (95% CI: 81.0%-93.0%), with some heterogeneity between studies (80% PI: 52.9%-98.1%). Willingness to pay was US$ 46.7 (95% CI: 25.9-67.5) per vaccine recipient. There were differences between continents, with higher acceptance in the Americas.

CONCLUSIONS

We were able to obtain global estimates of vaccine acceptance and willingness to pay and identify the associated factors that influence these values. This knowledge is relevant for the planning of future vaccination strategies.

Parents' intention to vaccinate their preschool children against COVID-19: Combining the health belief model and the theory of planned behavior

The vaccination rate of COVID-19 in preschool children is low, and parents' intention to vaccinate their children is also low due to multiple factors. This study aimed to establish an integrated model based on the Health Belief Model (HBM)and Theory of Planned Behavior (TPB), to explore the factors influencing parents' intention to vaccinate their preschool children with the first and second doses of COVID-19 vaccines. A total of 1264 parents of preschool children from 10 kindergartens participated in this study. Hierarchical multiple logistic regression was used to analyze the intention separately. For the integrated model with the first dose of vaccine of COVID-19, introducing the HBM variable in model 1 explained 33.98% of the variance (F = 398.71, p < .001), then upon adding the TPB variable in model 2, the explanation of variance increased to 41.93% (F = 491.94, p < .001) and parents' intention were associated with their perceived barriers, cues to action, and subjective norms. For the integrated model with the second dose of vaccine of COVID-19, introducing the HBM variable in Model 1 explained 23.76% of the variance (F = 68.82, p < .001), then upon adding the TPB variable in model 2, the explanation of variance increased to 26.67% (F = 77.24, p < .001), and parents' intention was associated with cues to action and subjective norms. The combination of the two theories improves the explanatory power of parents' intention to vaccinate their preschool children against COVID-19, and provides a basis for the development of effective interventions for vaccination of COVID-19 for preschool children.

Choice preference and willingness to pay for COVID-19 vaccination in Namibia

Background

Namibia has not been spared from the coronavirus (COVID-19) pandemic, and as intervention the Namibian government has rolled out vaccination programmes. This study was conducted before the roll out of these vaccines to assess the preference for COVID-19 vaccinations. Stated preference studies provide information about social demand, access, willingness-to-pay and financing for future COVID-19 vaccination.

Methods

A stated choice experiment (SCE) survey was administered to a sample of 506 participants from Namibia's general population between October 2020 and December 2020. Participants were asked to make a series of hypothetical choices and estimate their preference for different attributes of a vaccine. A latent class model was used to analyse the SCE data. The study also assessed anti-vaccination behaviour, past vaccination behaviour, impacts of COVID-19 on mental and physical health and Willingness-To-Pay (WTP) measures. The WTP measures were captured as out-of-pocket and further calculated using the marginal rate of substitution method in SCE.

Results

Data from 269 participants was included in the analysis. Vaccine side effects (40.065), population coverage (4.688), payment fee to receive vaccine immediately (3.733) were the top three influential attributes for vaccine preferences. Accordingly, increases in mild and severe side effects of vaccine options had negative impacts on utility; with an average WTP of N$728.26 to reduce serious side effects. The average WTP to receive a high-quality vaccine with 90% efficient was found to be N$233.11 (US$15.14). Across classes, there was a strong preference for vaccines with high effectiveness over longer durations of time.

Conclusions

The results provide useful information for the Namibian government to improve the current strategies for vaccine rollout interventions.

Vaccine Uptake to Prevent Meningitis and Encephalitis in Shanghai, China

Multiple vaccines may prevent meningitis and encephalitis (M/E). In China, the meningococcal vaccine and Japanese encephalitis vaccine (JEV) have been included in the expanded program of immunization (EPI). The pneumococcal vaccine, Haemophilus influenzae type b (Hib) vaccine, rotavirus vaccine, and enterovirus 71 (EV-71) vaccine are non-EPI vaccines and are self-paid. We aim to investigate the uptake of these M/E vaccines in children and the related knowledge and health beliefs among family caregivers. A total of 1011 family caregivers with children aged 1-6 years in Shanghai, China were included in the study. The uptake of the pneumococcal vaccine, Hib-containing vaccine, rotavirus vaccine, and EV-71 vaccine remained at 44.0-48.1% in children, compared with the higher uptake of the meningococcal vaccine (88.8%) and JEV (87.1%). Moreover, family caregivers had limited knowledge on the M/E pathogens and possible vaccines. Their health beliefs were moderate to high. Then, a health belief model (HBM) and a structural equation model were established. The uptake of four non-EPI vaccines was significantly influenced by family income (β = 0.159), knowledge (β = 0.354), self-efficacy (β = 0.584), and perceived susceptibility (β = 0.212) within an HBM. Therefore, it warrants further improving the uptake rate for these non-EPI vaccines to prevent potential M/E in children. A specific health promotion may empower the caregivers' decision-making on childhood vaccination.

Cost-Effectiveness of COVID-19 Sequential Vaccination Strategies in Inactivated Vaccinated Individuals in China

To effectively prevent and control the COVID-19 pandemic, countries have adopted a booster vaccination strategy. This study aimed to estimate the cost-effectiveness of sequential booster COVID-19 vaccination compared to two-dose inactivated vaccination in China from a societal perspective. A Markov model was developed to estimate the cost-effectiveness of sequential vaccination, including two doses of an inactivated vaccine followed by a booster shot of an inactivated vaccine, adenovirus vectored vaccine, protein subunit vaccine, or mRNA vaccine. The incremental effects of a booster shot with an inactivated vaccine, protein subunit vaccine, adenovirus vectored vaccine, and mRNA vaccine were 0.0075, 0.0110, 0.0208, and 0.0249 QALYs and saved costs of US$163.96, US$261.73, US$583.21, and US$724.49, respectively. Under the Omicron virus pandemic, the sequential vaccination among adults and the elderly (aged 60-69, 70-79, over 80) was consistently cost-saving, and a booster shot of the mRNA vaccine was more cost-saving. The results indicate that the sequential vaccination strategy is cost-effective in addressing the COVID-19 pandemic, and improving vaccination coverage among the elderly is of great importance in avoiding severe cases and deaths.

Exploring the Association between Negative Emotions and COVID-19 Vaccine Acceptance: A Cross-Sectional Analysis of Unvaccinated Adults in Sweden

The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on individuals’ mental health. This study aimed to investigate how negative emotions toward the COVID-19 pandemic, including feeling anxious, depressed, upset, and stressed, were associated with COVID-19 vaccine acceptance in Sweden. The study is a cross-sectional online survey conducted between 21–28 May 2021, using three nested hierarchical logistic regression models to assess the association. The study included 965 unvaccinated individuals, 51.2% (n = 494) of whom reported their intention to get vaccinated. We observed graded positive associations between reported negative emotions and vaccine acceptance. Individuals who experienced economic stress had lower odds of vaccine acceptance while having a positive opinion of the government’s response to COVID-19 was associated with higher odds of being vaccine-acceptant. In conclusion, unvaccinated individuals experiencing negative emotions about the pandemic were more willing to get the vaccine. On the contrary, those with a negative opinion about the government’s response, and those that had experienced economic stress were less likely to accept the immunization.

Willingness to Pay for a COVID-19 Vaccine

BACKGROUND

The coronavirus disease (COVID-19) pandemic has considerably affected the lives of people worldwide, impacting their health and economic welfare, and changing the behavior of our society significantly. This situation may lead to a strong incentive for people to buy a vaccine. Therefore, a relevant study to assess individuals' choices and the value of change in welfare from a COVID-19 vaccine is essential.

OBJECTIVE

This study aimed to estimate the willingness-to-pay (WTP) value for a vaccine for COVID-19. We also identify the variables that influence individual vaccination decisions, which could be used in the design of vaccination promotion strategies.

METHODS

We use the contingent valuation method in its double-bounded dichotomous choice format. The estimation coefficients are calculated according to the maximum likelihood method under the assumption of a probit distribution. The sample consisted of 531 individuals, mainly from middle- and high-income socioeconomic groups from Chile between enrolled between 10 July and 10 August 2020.

RESULTS

The results show a high WTP for the COVID-19 vaccine, with a value up to US$232. Income and education levels and having family members with COVID-19 increased the likelihood of persons paying for a vaccine. There is also a greater fear as the pandemic progresses that people will get sick from COVID-19.

CONCLUSIONS

The high WTP value creates an opportunity for formulating public health policy. The results of this study suggest that governments can provide the vaccine free to low-income groups and allow those with higher incomes to acquire the vaccine through the private sector by paying. This will be useful especially for countries with economic difficulties.